GIS used to map irrigation districts, plan rehabilitation projects
By Rachel Alexander
Experts with Texas Cooperative Extension are working to decrease water demanded by agriculture in the Lower Rio Grande Valley reducing water losses in the canal system and providing methods for using less water on croplands.
Research indicates that 68 billion gallons of water could be saved by advanced management and rehabilitation of irrigation canal systems. A technical assistance program coordinated by Extension is helping irrigation districts use a geographic information system (GIS) to manage water accounts and plan rehabilitation projects.
The GIS uses mapping software to assemble, organize and display geographically referenced information, such as the size of irrigated acreage or the capacity of pipelines.
Extension Agricultural Engineer Guy Fipps said that prior to the technical assistance program, many irrigation districts in the Valley relied on outdated maps and maintained few records about their distribution networks. Now, he said, eight districts, including those in San Juan, Mercedes, San Benito and Brownsville have integrated the GIS into daily operations.
In San Juan, fields and their account numbers link the GIS to water account databases, providing automatic updates as changes occur. As a result, Fipps said, irrigation district personnel have immediate access to the latest information and can better interact with customers.
Maintenance crews and canal riders also obtain maps of specific areas related to their work. Irrigation district personnel in Brownsville are using the GIS to create customized notebooks with maps of field boundaries and valves.
"Photographs, diagrams and other records of facilities and legal descriptions have been linked to the GIS for quick display and use," Fipps said. "With a click of the mouse, maintenance records and photos of work orders are documented."
Extension Associate Eric Leigh said that in Brownsville and other irrigation districts, where rehabilitation projects are under way to replace canals with pipelines and reline canals, the GIS has reduced the size and cost of these projects.
"Prior to the use of the GIS, capacity requirements for new pipelines were based on total land area, which included non-farmed land," he said. "Maps created with the GIS enable the irrigation districts to determine capacity requirements based on actual field size and soil type, which optimizes pipeline sizes and reduces the cost."
The technical assistance program is funded in part through the Rio Grande Basin Initiative. Administered by the Texas Water Resources Institute, the Rio Grande Basin Initiative is a joint project of the Texas A&M University System Agriculture Program and the New Mexico State University College of Agriculture and Home Economics. The federally funded initiative is focused on research and Extension activities to improve irrigation efficiency and water conservation.
Irrigation districts also rely on the GIS for resolving boundary disputes, predicting water use patterns and conducting other analyses. In addition to the technical assistance program, Extension is working with the districts through demonstration projects to improve water accounting and evaluate needs for rehabilitation. Through these demonstrations, Extension introduced modern flow meters and water measurement structures for on-farm water accounting.
